Transmission with non-coaxial output

ABSTRACT

A vehicle transmission having an input shaft, a main shaft, a countershaft and an output shaft mounted for rotation around axes of rotation and a plurality of gear wheels mounted on the countershaft and the output shaft for the transmission of torque from the input shaft to the output shaft at a gear ratio provided by the gears. The axis of rotation of the main shaft and the axis of rotation of the output shaft do not lie along the same axis and the distance between the axes of rotation of main shaft and output shaft is determined by the reduction ratio of a constant gear wheel pair located between the countershaft and the output shaft.

The invention relates to a transmission having a main shaft and acountershaft.

BACKGROUND OF THE INVENTION

From the prior art, transmissions are already known having one inputshaft, one main shaft, one countershaft and one output shaft in which inthe input shaft, the main shaft and the output shaft are mounted on acommon axis of rotation. Transmissions of this kind can have a one pieceinput and output shaft or a one piece main and output shaft. Atransmission of this kind is shown, e.g. in DE 195 38 192.

The numbers of teeth on the gear wheels of the shafts are determined onthe basis of the desired reduction ratios. This implies specificdiameter ratios of the gear wheels of the parallel shafts relative toeach other and thus also the spatial distance between the shafts. Thusthe gear wheel pair consisting of the first gear wheel upon the inputshaft and the first gear wheel upon the countershaft, seen from theinput side, are configured so that a gear wheel of very small diameterupon the input shaft is associated with a gear wheel of very largediameter upon the countershaft. This pair of gear wheels makes atransmission of a great torque at a lower speed level possible, but agreat spatial distance results in a large size of the transmissionhousing which can lead to difficulties in the installation space for thevehicle manufacturer.

SUMMARY OF THE INVENTION

The problem on which the invention is based is to reduce theinstallation space needed for a transmission and lead to a smaller sizeof the transmission.

It is proposed, according to the invention, to non-rotationally mount agear wheel, upon the output shaft of the transmission, which is drivenby a gear wheel non-rotationally connected with the countershaft, thegear wheel pair forming one constant. The input shaft of thetransmission is non-rotationally connected with the main shaft. The axisof rotation of the input shaft and the axis of rotation of the mainshaft are equal and the axis of rotation of the main shaft and the axisof rotation of the output shaft do not form the same axis. The distancebetween the axes of rotation of main shaft and output shaft isdetermined by the reduction ratio of the gear wheel pair of theconstant.

In an advantageous development, the gear wheel pair of the constant islodged in a separate transmission housing in order to make replacementof the gear wheel pair possible.

In another advantageous development for driving a hydrodynamic retarder,an auxiliary output shaft is provided which can be driven directly bythe main shaft or the countershaft and serves to achieve a highrotational speed of the retarder without intercalation of a high drivingstep.

For a splitter transmission, an advantageous development shows upon theoutput shaft when a gear shift device subdivides the gear steps in halfspeed steps.

In an advantageous development, a range-change group transmission, inthe form of a planetary transmission, is provided next to the gear wheelpair of the constant for enlarging the total spreading of thetransmission.

By shifting the arrangement of a constant of the transmission to theoutput side end of the transmission and the non-coaxiality of the axesof rotation of main shaft and output shaft, the diameters of the largewheel of the transmission are reduced. With reduced diameters, theweight of the gear wheels thereby can be reduced and the axial distancesof the parallel shafts shortened, which results in a smaller size forthe transmission. A reduced size of the transmission means in thisinstance advantageously less weight and more installation space in thevehicle. At the same time, less expenditure in material and processingfor smaller gear wheels and a housing results in lower cost. The smallermasses of the gear wheels to move and synchronize, when shifting, resultin a level of shifting effort clearly. The synchronizing devices alsoare less apt to fail, since the masses to be synchronized are smaller.By virtue of the smaller gear wheels on the input-side end of thecountershaft with a small axial distance between input shaft and mainshaft and the countershaft, the rotational speeds of the countershaftare at a higher level. A reduced torque level, on which the structuralparts of the transmission must be designed, is obtained thereby in thelargest part of the transmission. A high torque only generates in theoutput constant when an enlarged axial distance exists between theoutput shaft and the countershaft. With the inventive arrangement, thetransmission input torque can be designed the same size for transmissionconstructions having direct drive and overdrive versions.

As a result of a one piece design for the input shaft and the mainshaft, the pivot bearing of the main shaft and the input shaft of theprior art can be eliminated. The gear wheel pair mounted on thetransmission end can be configured so as to be inserted as a separateunit, after the other transmission housing, making a modular design oftransmissions having different wheel pairs on the output constantpossible.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail with reference to drawings wherein:

FIG. 1 is a transmission according to the prior art;

FIG. 2 is a diagrammatic arrangement of a transmission according to theinvention; and

FIG. 3 is an arrangement according to FIG. 2 with splitter transmission.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an enlarged illustration of a transmission 6 according tothe prior art having, e.g. five forward gears and one reverse gear. Witha control lever 18 access is had to the three gearshift rods 20, 22 and24 which, via gear shift forks, move the synchronizing devices 26, 28and 30 to the desired gear shift positions. Thus the synchronizingdevice 30 engages the reverse gear and the first transmission ratio. Thesynchronizing device 26 engages the second and third gear steps whilethe synchronizing device 28 is used to engage the fourth and fifth gearsteps. The input shaft 32 is supported in the transmission housing 34 bya support such as the bearing 36 shown here. The main shaft 38 issupported in the transmission input shaft 32 by a bearing 40 and in thehousing 34 by a support such as a bearing 42 shown here. The reversedirection of rotation for the reverse gear is obtained by anintermediate gear 44 the toothing of which meshes with the toothing ofthe reverse gear wheel upon the main shaft 38 and the toothing of thecountershaft 46. The other toothings of the gear wheels, on the mainshaft 38, likewise engage with corresponding toothings of thecountershaft 46 for the forward gear ratio. A toothing is additionallyprovided on the transmission input 32 for mounting a clutch body 54.

In an advantageous development, the combination of transmission 60 andconstant gear wheels 108, 110 may be supplemented by the provision of aRange Change Group Transmission 60RCG next to the gear wheel 110 of theconstant, wherein the Range Change Group Transmission 60RCG may beimplemented as a Planetary Transmission 136 in a conventional manner andas illustrated, thereby enlarging the total gear ratio spread of thetransmission. In this regard, it is well known to those of skill in thearts that a planetary transmission may be operative and used to providetwo, selectable constant gear ratios, while a multiple gear ratiotransmission, such as transmission 106 shown in FIG. 2, is operative andused to provide a set of selectable gear ratios defining a range of gearratios. It is further well known to those of skill in the relevant artsthat the connection of a planetary transmission in “series” with amultiple gear ratio transmission will provide, in combination, a twostage transmission wherein one stage is comprised of the multiple gearratio transmission and the second stage is comprised of the planetarytransmission. The resulting two stage transmission will therefore havetwo ranges of gear ratios, wherein the gear ratios within either of thetwo ranges are determined and provided by the multiple gear ratiotransmission and the range, that is, a selected one of either of the tworanges, is determined and selected by the planetary transmission. Itwill be well understood by those of skill in the relevant arts that thetwo gear ratio ranges may be separate or may overlap or may abut,depending upon the gear ratio range of the multiple gear ratio stage,but that the effect of the addition of the planetary transmission willbe to increase the total gear ratio spread, that is, the total gearratio range, of the combined transmission. For this reason, theplanetary gear transmission is often referred to as a “range-changegroup transmission”, that is, as a transmission selecting and changing aset of transmission gear ratios from among two or more sets oftransmission gear ratios wherein the gear ratios within a given set arecommon to all the sets of gear ratios and are provided by anothertransmission or stage of the transmission. The details of a PlanetaryTransmission 136 and the interconnection of a Planetary Transmission 136with other transmissions or transmission components will not bediscussed in further detail herein as such are well known to andunderstood by those of ordinary skill in the relevant arts. FIG. 3 showsan enlarged arrangement, in comparison with that of FIG. 2, with asplitter transmission 134 in the housing 106 to form a second constant.A synchronizing device 126 is provided upon the output shaft 112 bywhich the gear wheel 111 or the gear wheel 128 can be optionallynon-rotationally connected with the output shaft. The gear wheel 108 isnon-rotationally situated jointly with a gear wheel 130 upon a shaft132.

FIG. 2 shows a diagrammatic illustration of the transmissionconstructions according to the invention. A transmission 60 has ahousing 62 in which an input shaft 64 projects. The input shaft 64 isdesigned integral with the main shaft 66 of the transmission 60. On themain shaft 66 seven gear wheels 68, 70, 72, 74, 76, 78, 80 are mountedof which the gear wheels 68, 70, 72, 74 can loosely rotate upon the mainshaft 66 while the gear wheels 76, 78, 80 are permanentlynon-rotationally connected with the main shaft 66. A synchronizingdevice 82 is provided between the gear wheels 68 and 70 by which thegear wheel 68 or the gear wheel 70 can be optionally non-rotationallyconnected with the main shaft 66. A synchronizing device 84 is providedbetween the gear wheels 72 and 74 by which the gear wheel 72 or the gearwheel 74 can be optionally non-rotationally connected with the mainshaft 66.

Seven gear wheels 88, 90, 92, 94, 96, 98, 100 are likewise provided uponthe countershaft 86 of which the gear wheels 88, 90, 92, 94 arepermanently non-rotationally connected with the countershaft 86. Asynchronizing device 102 is provided between the gear wheels 96 and 98by which the gear wheel 96 or the gear wheel 98 can be optionallynon-rotationally connected with the countershaft 86. For the reversegear, the gear wheel 100 meshes, for a reverse direction of rotation,with an intermediate gear 104 which, in turn, meshes with the gear wheel80 upon the main shaft 66. The gear wheel 98 meshes with a gear wheel120 upon an auxiliary output shaft 122 by which a retarder 124 isdriven. Due to the large diameter of the gear wheel 98, the auxiliaryoutput shaft 122 is driven at a high rotational speed.

In the illustration shown here, one other housing 106 is provided nextto the transmission housing 62. A gear wheel pair consisting of two gearwheels 108 and 110 is mounted in the housing 106, the gear wheel 108 isnon-rotationally connected with the countershaft 86. The gear wheel 110is permanently non-rotationally connected with the output shaft 112, butthe gear wheels 108 and 110 can also be situated within the adequatelyconfigured transmission housing 62. Gear wheel 110 and output shaft 112rotate around an imaginary axis of rotation 114. The main shaft 66 andthe gear wheels mounted thereon, the same as the input shaft 64, rotatearound an axis of rotation 116. Both axes of rotation 114 and 116 arenot coaxial with respect to each other, but are separated by an axialdistance 118.

As described above, and as shown in FIG. 2, in an advantageousdevelopment, a range-change group transmission 136, in the form of aplanetary transmission, is provided next to the gear wheel pair 108, 110of the constant for enlarging the total spreading of the transmission.FIG. 3 shows an enlarged arrangement, in comparison with that of FIG. 2,with a splitter transmission 134 in the housing 106 to form a secondconstant. A synchronizing device 126 is provided upon the output shaft112 by which the gear wheel 111 or the gear wheel 128 can be optionallynon-rotationally connected with the output shaft. The gear wheel 108 isnon-rotationally situated jointly with a gear wheel 130 upon a shaft132.

Reference numerals 6 transmission 84 synchronizing device 18 controllever 86 countershaft 20 gearshift rod 88 gear wheel 22 gearshift rod 90gear wheel 24 gearshift rod 92 gear wheel 28 synchronizing device 94gear wheel 30 synchronizing device 96 gear wheel 32 transmission inputshaft 98 gear wheel 34 transmission housing 100 gear wheel 36 bearing102 synchronizing device 38 main shaft 104 intermediate gear 40 bearing106 housing 42 bearing\44 intermediate gear 108 gear wheel 46countershaft 110 gear wheel 54 clutch body 111 gear wheel 60transmission 112 output shaft 62 transmission housing 114 axis ofrotation 64 input shaft 116 axis of rotation 66 main shaft 118 axialdistance 68 gear wheel 120 gear wheel 70 gear wheel 122 auxiliary outputshaft 72 gear wheel 124 retarder 74 gear wheel 126 synchronizing device76 gear wheel 128 gear wheel 78 gear wheel 130 gear wheel 80 gear wheel132 shaft 82 synchronizing device 134 splitter transmission

What is claimed is:
 1. A vehicle transmission (6, 60) comprising acountershaft transmission having: one input shaft (32, 64), one mainshaft (38, 66), one countershaft 46, 86), and one output shaft (112);wherein the main shaft (38, 66) has a plurality of loose gear wheels(68, 70, 72, 74) and a plurality of fixed gear wheels (76, 78, 80)mounted thereon; the countershaft (46, 86) has a plurality of loose gearwheels (96, 98) and a plurality of fixed gear wheels (88, 90, 92, 94)mounted thereon; each of the input shaft, main shaft, countershaft andoutput shaft is rotatably mounted around an axis of rotation (114, 116);an output shaft output gear wheel (110, 111, 128) is non-rotatablymounted upon the output shaft (112) and is driven by a countershaftoutput gear wheel (108, 130) non-rotationally mounted on thecountershaft (86); the output shaft output gear wheel (110, 111, 128)and the countershaft output gear wheel (108, 130) together form aconstant output gear wheel pair; the input shaft (64) of thetransmission (60) is non-rotationally connected with the main shaft(66);the input shaft axis of rotation (116) and the main shaft axis ofrotation (116) are coincident with one another; the output shaft axis ofrotation (114) is spaced from the main shaft axis of rotation (116) anda spacing distance (118) between the main shaft and output shaft axes ofrotation (114, 116) is determined by a reduction ratio of the constantoutput gear wheel pair (108-110, 108-111, 130-128); and the constantoutput gear wheel pair (108-110, 108-111, 130-128) is accommodatedwithin a separate transmission housing (106) to facilitate replacementof the constant output gear wheel pair (108-110, 108-111, 130-128).
 2. Avehicle transmission (6, 60) comprising a countershaft transmissionhaving: a single input shaft (32, 64), a single main shaft (38, 66), asinge countershaft (46, 86), and a single output shaft (112); whereinthe single main shaft (38, 66) has a plurality of loose gear wheels (68,70, 72, 74) and a plurality of fixed gear wheels (76, 78, 80) mountedthereon; the single countershaft (46, 86) has a plurality of loose gearwheels (96, 98) and a plurality of fixed gear wheels (88, 90, 92, 94)mounted thereon; each of the single input shaft, single main shaft,single countershaft and single output shaft is rotatably mounted aroundan axis of rotation (114, 116); an output shaft output gear wheel (110,111, 128) is non-rotatably mounted upon the single output shaft (112)and is driven by a countershaft output gear wheel (108, 130)non-rotationally mounted on the single countershaft (86); the outputshaft output gear wheel (110, 111, 128) and the countershaft output gearwheel (108, 130) together form a constant output gear wheel pair; thesingle input shaft (64) of the transmission (60) is non-rotationallyconnected with the single main shaft (66); the single input shaft axisof rotation (116) and the single main shaft axis of rotation (116) arecoincident with one another; the output shaft axis of rotation (114) isspaced from the man shaft axis of rotation (116) and a spacing distance(118) between the main shaft and output shaft axes of rotation (114,116) is determined by a reduction ratio of the constant output gearwheel pair (108-110, 108-111, 130-128); and an auxiliary output shaft(122) is provided for driving a hydrodynamic retarder (124) and theauxiliary output shaft (122) is driven by one of the main shaft (66) andthe countershaft (86) to achieve a high rotational speed of the retarder(124) without intercalation of a high driving step.
 3. A vehicletransmission (6, 60); comprising: a countershaft transmission having: aninput shaft (32, 64), a main shaft (38, 66), a countershaft (46, 86),and an output shaft (112); wherein the main shaft (38, 66) has aplurality of loose gear wheels (68, 70, 72, 74) and a plurality of fixedgear wheels (76, 78, 80) mounted thereon; the countershaft (46, 86) hasa plurality of loose gear wheels (96, 98) and a plurality of fixed gearwheels (88, 90, 92, 94) mounted thereon: each of the input shaft, mainshaft, countershaft and output shafts is rotatably mounted around anaxis of rotation (114, 116); an output shaft output gear wheel (110,111, 128) is non-rotatably mounted upon the output shaft (112) and isdriven by a countershaft output gear wheel (108, 130) non-rotationallymounted on the countershaft (86); the output shaft output gear wheel(110, 111, 128) and the countershaft output gear wheel (108, 130)together form a constant output gear wheel pair; the input shaft (64) ofthe transmission (60) is non-rotationally connected with the main shaft(66); the input shaft axis of rotation (116) and the main shaft axis ofrotation (116) are coincident with one another; and the output shaftaxis of rotation (114) is spaced from the main shaft axis of rotation(116) and a spacing distance (118) between the main shaft and outputshaft axes of rotation (114, 116) is determined by a reduction ratio ofthe constant output gear wheel pair (108-110, 108-111, 130-128).
 4. Thevehicle transmission (6, 60) according to claim 3, wherein asynchronizing device (126), for a splitter transmission (134), isprovided upon the output shaft (112) to subdivide gear steps intointermediate gear steps.
 5. The vehicle transmission (6, 60) accordingto claim 3, wherein a range group transmission (136) is providedadjacent to the constant output gear wheel pair (108-110, 108-111,130-128) to enlarge a total spread of the vehicle transmission (60).